Rising costs of oil and electrical power are inducing the development of energy efficient systems and controls. Each year, mainly during the hot summer months, electric utilities in metropolitan areas face periods of peak power demand that can exceed the available power supply. The result can be rolling blackouts or brown-outs that can severely affect businesses, schools and basic operations within a city or across a large part of the country. The problem will only continue to grow worse as the need for electricity continues to grow faster than the ability to create new supplies.
One general concept to reduce the load on the power grid as well as reduce customer cost during these high demand, high cost periods, is to introduce a system of control known as demand response. The general concept is that during times of rising or peak demand, and therefore cost, the electric companies would send a signal to customers informing them that the price of electricity is rising or will rise. As used in the specifications, “signals” refer to any mode of communication. The customer can then respond by reducing their load on the power grid throughout their building to not only ease the burden on the power grid, but also to avoid paying the high cost of electricity on non-essential items.
The general concept can be as basic as a building owner receiving an email or phone call from the electric company and then physically walking around turning off lights and appliances in the building. The foregoing example obviously has drawbacks in that the electric power company is limited in its ability to contact customers and the customer also must be available to physically receive the signal and then roam throughout the building to power down appliances and systems.
An alternative solution that is emerging involves the customer setting up a network of appliances and machines that can be remotely controlled at a single access point for each room, zone or even for an entire building. The electric power company can send out a signal that will be received by a receiver set up by the customer. At this time, the customer will know a period of high demand is beginning and then, from each access point, can reduce the power load of each room, zone or building to avoid paying the high rates for electricity
One of the main contributors to a building's electric use is the lighting system. Products are currently coming onto the market that allow lighting systems to be remotely turned on and off or even dimmed down various levels. Most of these products are either for compact fluorescent lamps (CFLs) or other fluorescent lamps, since halogens and incandescent lights are so inefficient that their use is becoming increasingly less common. Compact fluorescent lamps or other fluorescent lamps can be dimmed remotely to provide energy and cost savings. One problem with dimming these types of lamps is that, as they are dimmed down to save energy, their efficacy, i.e., lumens per watt, drops substantially. This severely limits the potential gains that can be realized with demand response dimming of compact fluorescent lamps or other fluorescent lamps.
However, the main problem with merely dimming lights is that there is a minimum level of lighting that must be maintained to provide a safe environment. The Illumination Engineering Society of North America and comparable organizations in other locations, have many guidelines that are generally used across the industry as the standard for how to light spaces. These guidelines set limits for various spaces, warehouses, schools, nursing homes, office buildings, etc, that balance safety, comfort, and production so that a space is adequately lit for a majority of its occupants. These guidelines only provide a minimum light level and the usual practice is to illuminate most spaces above the minimum levels required, to further improve safety, comfort, and work production.
Merely dimming light levels below a certain point to save energy not only affects comfort and productivity but poses a safety hazard. In fact, many insurance companies in the U.S. require signed contracts stating that a minimum light level will be maintained in a building. The reason is that exposure to liability can be large if the light level in work spaces drops below a certain level and an accident occurs. This is in addition to numerous studies which have proven that decreasing illumination below certain light levels has a negative effect on productivity. Accordingly, the present inventors have discerned that there Is a need to balance a reduction In energy usage with both the safety and productivity of the people in spaces being illuminated.